package auth

import (
	"encoding/json"
	"fmt"
	"os"
	"time"
)

// claudeCredentialsJSON matches the structure of ~/.claude/.credentials.json.
type claudeCredentialsJSON struct {
	ClaudeAiOauth struct {
		AccessToken      string `json:"accessToken"`
		RefreshToken     string `json:"refreshToken"`
		ExpiresAt        int64  `json:"expiresAt"`
		SubscriptionType string `json:"subscriptionType"`
	} `json:"claudeAiOauth"`
}

// LoadDefaultCredentials reads credentials from ~/.claude/.credentials.json.
// Returns nil, nil if the file does not exist.
func LoadDefaultCredentials() ([]*Credential, error) {
	path, err := DefaultCredentialPath()
	if err != nil {
		return nil, nil
	}

	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}

	var cf claudeCredentialsJSON
	if err := json.Unmarshal(data, &cf); err != nil {
		return nil, err
	}

	oauth := cf.ClaudeAiOauth
	if oauth.AccessToken == "" {
		return nil, fmt.Errorf("no access token in %s", path)
	}

	cred := &Credential{
		ID:           "claude-native",
		Email:        oauth.SubscriptionType,
		AccessToken:  oauth.AccessToken,
		RefreshToken: oauth.RefreshToken,
		ExpiresAt:    time.UnixMilli(oauth.ExpiresAt),
		FilePath:     path,
	}

	return []*Credential{cred}, nil
}